For the functional A[ f ] = âˆ‘k=1 ak f (zk) , we give necessary and sufficient conditions over the real numbers zk , such that, the inequality A[ f ] 0 , holds for some classes of convex functions.â€¦ (More)

We construct a bijective continuous area preserving map from a class of elongated dipyramids to the sphere, together with its inverse. Then we investigate for which such solid polyhedrons the areaâ€¦ (More)

First a new mathematical approach is presented to evaluate the electric and magnetic field of the lightning, via engineering model with variable shape return stroke channel; next, an inverseâ€¦ (More)

We characterize the functions defined on a weighted space, which are uniformly approximated by a sequence of positive linear operators and we obtain the range of the weights which can be used forâ€¦ (More)